(1) Field of the Invention
The invention relates to a key structure, and more particularly, to a noise reduction key structure that can reduce noise of triggering keys
(2) Description of the Prior Art
In modern life, there are many kinds of electronic produces that are widely used by people, and people usually operate these electronic produces through various interfaces, for example, keyboards, mice, touch panel, and hand-writing board. In daily life, the most widely input device in the electronic produces is keyboards. Nowadays, computers still use pressing keyboards, moving mice, and touching panels to control inputs.
First, please refer to FIG. 1 which shows a key structure in the prior art. As shown in FIG. 1, an electronic device 1 has a housing 11, a substrate 12, and two key structures 10a, 10b, wherein the housing 11 has two key openings 110a, 110b, the key structure 10a includes a switch element 14a and a key portion 13a, the key structure 10b includes a switch element 14b and a key portion 13b. Accordingly, the electronic device 1 in the FIG. 1 is a structure that shows a part of touch board of a notebook computer, and the substrate 12 is a printed circuit board.
The switch element 14a, 14b are mounted on the substrate 12, the key portions 13a, 13b are respectively mounted in the key openings 110a, 110b, and are exposed to outside. The key portions 13a, 13b have an elastic restoration force. When the up sides of the key portions 13a, 13b are pressed, then down sides the key portions 13a, 13b will trigger the switch elements 14a, 14b. When the up sides of the key portions 13a, 13b are not pressed, then the key portions 13a, 13b will return to their original positions through the elastic restoration force.
However, when triggering the key structures 10a and 10b, there is a noise that bothers people. The noise is from an inner structure of the switch elements 14a, 14b. Because the switch elements 14a, 14b are different from each other, the reasons that cause the noise are different. The following will take tact switches for example to find out the reasons that cause the noise.
Please refer to FIG. 2 which shows a structure of a switch element 14. As shown in FIG. 2, the switch element 14 includes a key cap 141, a metal piece 142 and a pedestal 143. The pedestal 143 has a first electrode 151 and two second electrodes 152a, 152b. The metal piece 142 is an O-shaped electrical conductive piece, and covers an inner of the pedestal 143, and the key cap 141 is installed on the metal piece 142.
Again, please refer to FIGS. 3A and 3B, both of which show a sectional views of the switch element 14 in FIG. 2. As shown in FIG. 3A, the switch element 14 is not triggered yet, and the first electrode 151 and second electrode 152a, 152b are not electrically conductive yet. As shown in FIG. 3B the switch element 14 is triggered, the key cap 141 is pressed down by an external force. At that time, down edge of the key cape 141 will exert a force on an up side of the metal piece 142 to make the metal piece 142 deform, and further make the first electrode 151 and these two electrodes 152a, 152b electrically conductive. When the force that is exerted on the upper side of the key cap 141 is removed, then the metal piece will return back to its original O-shaped through the elastic restoration force, and thus the key cap 141 will return back to its original position, too.
The noise is produced during the time of deformation process of the metal piece 142; moreover, the electronic device 1 is a close space which can be a resonance space that can produce resonance, and further amplify such a noise.
The noise from the switch element 14 can be obviously observed in notebook computers and mice, because computers and their peripherals are needed by modern people in work and leisure time, and people always click and input through triggering keys, so that the noise can make the user and people who surround the user upset. Therefore, how to utilize material and various structure to further reduce and even eliminate such a noise is a top priority for research and development engineers to solve, so that user who uses the electronic device 1 and people who surround the user cannot be bothered by the noise.